TM4C123GE6PZ Datasheet, PDF (721/1445 Pages) Texas Instruments – Tiva™ TM4C123GE6PZ Microcontroller

Tiva^™ TM4C123GE6PZ Microcontroller
11.3
11.3.1
Functional Description
The main components of each GPTM block are two free-running up/down counters (referred to as
Timer A and Timer B), two prescaler registers, two match registers, two prescaler match registers,
two shadow registers, and two load/initialization registers and their associated control functions.
The exact functionality of each GPTM is controlled by software and configured through the register
interface. Timer A and Timer B can be used individually, in which case they have a 16-bit counting
range for the 16/32-bit GPTM blocks and a 32-bit counting range for 32/64-bit Wide GPTM blocks.
In addition, Timer A and Timer B can be concatenated to provide a 32-bit counting range for the
16/32-bit GPTM blocks and a 64-bit counting range for the 32/64-bit Wide GPTM blocks. Note that
the prescaler can only be used when the timers are used individually.
The available modes for each GPTM block are shown in Table 11-3 on page 721. Note that when
counting down in one-shot or periodic modes, the prescaler acts as a true prescaler and contains
the least-significant bits of the count. When counting up in one-shot or periodic modes, the prescaler
acts as a timer extension and holds the most-significant bits of the count. In input edge count, input
edge time and PWM mode, the prescaler always acts as a timer extension, regardless of the count
direction.
Table 11-3. General-Purpose Timer Capabilities
Mode
Timer Use
Count
Direction
Counter Size
16/32-bit
GPTM
32/64-bit
Wide GPTM
Prescaler Size^a
Prescaler Behavior
16/32-bit 32/64-bit
(Count Direction)
GPTM Wide GPTM
Individual
One-shot
Concatenated
Up or Down
Up or Down
16-bit
32-bit
32-bit
64-bit
8-bit
16-bit
Timer Extension (Up),
Prescaler (Down)
-
-
N/A
Periodic
Individual
Up or Down
Concatenated Up or Down
16-bit
32-bit
32-bit
64-bit
8-bit
16-bit
Timer Extension (Up),
Prescaler (Down)
-
-
N/A
RTC
Concatenated Up
32-bit
64-bit
-
-
N/A
Edge
Count
Individual
Up or Down 16-bit
32-bit
8-bit
16-bit
Timer Extension
(Both)
Edge
Time
Individual
Up or Down 16-bit
32-bit
8-bit
16-bit
Timer Extension
(Both)
PWM
Individual
Down
16-bit
32-bit
8-bit
16-bit
Timer Extension
a. The prescaler is only available when the timers are used individually
Software configures the GPTM using the GPTM Configuration (GPTMCFG) register (see page 740),
the GPTM Timer A Mode (GPTMTAMR) register (see page 742), and the GPTM Timer B Mode
(GPTMTBMR) register (see page 746). When in one of the concatenated modes, Timer A and Timer
B can only operate in one mode. However, when configured in an individual mode, Timer A and
Timer B can be independently configured in any combination of the individual modes.
GPTM Reset Conditions
After reset has been applied to the GPTM module, the module is in an inactive state, and all control
registers are cleared and in their default states. Counters Timer A and Timer B are initialized to all
1s, along with their corresponding registers:
■ Load Registers:
– GPTM Timer A Interval Load (GPTMTAILR) register (see page 769)
June 12, 2014
721
Texas Instruments-Production Data